Abstract:
Soft soils are generally known for their extremely high compressibility, low stiffness & low
shear strength behavior; and cement treatment is one of the most commonly used techniques to treat such soils to acquire the required engineering behaviorand specifications to allow the structure to be placed safely on soft soils without undergoing large settlements. This research is focused on the evaluation of compressibility and shear strength properties of soft soil due to cement treatment at different cement contents and curing time. The soft soil used in this research was found to be too soft (SPT N=1) to collect the undisturbed samples at soil site. Therefore, disturbed representative samples were collected from the soil site located at KanjurMarg, Mumbai. The remolded specimens of collected soft soil with same in-situ water content and density were prepared in the laboratory by using slurry consolidation technique. A self-reacting pneumatic slurry consolidometer has been developed in the laboratory to produce the solid cylindrical specimens of fine grained soils. These slurry consolidated specimens were used to perform the UC (Unconfined Compression) tests and CRS (Constant Rate of Strain) tests to evaluate the shear strength and compressibility properties of soft soil before and after the cement treatment respectively. The Conventional 1-D consolidation test (oedometer) was found to be unsuitable for treated soft soil due to its long testing duration (~10 days), which caused major changes in compressibility properties of treated soil at chosen curing time.
This motivated the author to develop the 1-D CRS consolidation testing setup in the laboratory to evaluate the compressibility behavior of treated soft soils in few hours without any change in chosen curing time. A wide range of cement contents (2%, 4%, 6% & 8%) and curing time periods (1, 3, 7 & 28 days) were explored in this research to investigate the relationship of compressibility parameters, shear strength properties, cement content and curing time period for highly compressible soft soils.